The present invention relates to a display device with a touch screen having sensors arranged in a matrix which illuminates a liquid crystal display panel by a backlight light source or displays an image by spontaneous light-emitting elements, and more particularly, to control of backlight to realize an increased detection accuracy in the sensors or control of the spontaneous light-emitting elements.
Recent years have seen significant spread of a display panel which can be operated by touching the panel with use of a pen or operator's finger. As one of touch operation detecting systems, a system for building optical sensors into a liquid crystal display panel is enumerated. There is disclosed in SID′03 Digest “Active Matrix LCD with Integrated Optical Touch Screen” an LCD wherein, when an operator touches a panel with use of his finger or a stylus pen, a shade is produced on the display panel at its touched site by blocking external light coming into the display panel from its surface.
Also disclosed in EP 1 610 210 A1 (JP-A-2004-318819) is a display device which eliminates the influences of external light causing noise by utilizing a backlight light source when a touch operation by finger is detected.